Mr Hunt agreed the medical director would not be asked to speak to the media on the day the strike was declared “so long as” his letter underlined his opposition to the walk out.

Asked to confirm he was “happy” with changes, an official told the health service chief: “I am sure then that JH [Jeremy Hunt] will be interested to see the proposed final product; my hope is that if you are happy to make these changes we will be able to get him over the line.”

Health Secretary Jeremy Hunt (Image: PA)

The department insisted it was “absolutely right” that ministers insisted on Sir Bruce giving his “independent” view on how the health service would be able to respond.

But the Lib Dems called for the Cabinet Secretary to spearhead a probe into the row.

The party’s health spokesman Norman Lamb said: “In cases like this it is crucial to establish who had involvement in something that risks further damaging the Government’s relationship with junior doctors.

“This cannot be done by the department and I am calling for Sir Jeremy Heywood to set up a suitable inquiry that will command respect to look into this.

“The Government has to urgently resolve the dispute with junior doctors and must also set up an cross-party commission to confront the looming crisis facing the NHS and social care services so we can secure their future.”

A Department of Health spokesman said: “Industrial action of the kind planned by the British Medical Association creates a major safety risk for patients so it was absolutely right that ministers insisted on Sir Bruce Keogh giving his independent view of the NHS’ capacity to respond in the event of a major terrorist incident.”